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Table 6 Correlation between PIK3CA mutation type and clinical variables, including pathological response to chemotherapy

From: PIK3CA-activating mutations and chemotherapy sensitivity in stage II–III breast cancer

   Exon 9 mutation status Exon 20 mutation status
   Wild-type (n = 117) Mutation (n = 12) P valuea Wild-type (n = 117) Mutation (n = 11) P valuea
Pathological complete response (pCR) versus residual disease (RD)b RD 95 (82.6%) 10 (83.3%) 0.656 95 (82.6%) 8 (80.0%) 0.689
  pCR 20 (17.4%) 2 (16.7%)   20 (17.4%) 2 (20.0%)  
  Unknown 2 - - 2 1 -
Residual cancer burden 0 20 (22.0%) 2 (25.0%) 0.524 (0.513c) 20 (22.0%) 2 (28.6%) 0.243 (0.492c)
  I 7 (7.7%) 0 (0%)   7 (7.7%) 0 (0%)  
  II 37 (40.7%) 5 (62.5%)   37 (40.7%) 5 (71.4%)  
  III 27 (29.7%) 1 (12.5%)   27 (29.7%) 0 (0%)  
  Unknown 26 4   26 5  
HER2 status HER2- 104 (88.9%) 11 (91.7%) 0.617 104 (88.9%) 10 (90.9%) 0.659
  HER2+ 13 (11.1%) 1 (8.3%)   13 (11.1%) 1 (9.1%)  
Grade Grade 1–2 46 (47.4%) 4 (50.0%) 0.561 46 (47.4%) 6 (60.0%) 0.112
  Grade 3 51 (52.6%) 4 (50.0%)   51 (52.5%) 4 (40.0%)  
  Unknown 20 4 - 20 1 -
Nodal status Negative 29 (24.8%) 8 (66.7%) 0.023 29 (24.8%) 4 (36.4%) 0.761
  Positive 88 (75.2%) 4 (33.3%)   88 (75.2%) 7 (64.6%)  
Tumor size T0 1 (0.9%) 1 (8.3%) 0.322 1 (0.9%) 0 (0%) 0.854
  T1 7 (6.0%) 0 (0%)   7 (6.0%) 0 (0%)  
  T2 50 (50.4%) 6 (50.0%)   59 (50.4%) 6 (54.5%)  
  T3 18 (15.4%) 2 (16.7%)   18 (15.4%) 1 (9.1%)  
  T4 32 (27.4%) 3 (25.0%)   32 (27.4%) 4 (36.4%)  
Ethnicity Asian 2 (1.7%) 0 (0%) 0.544 2 (1.7%) 1 (9.1%) 0.290
  Black 11 (9.4%) 0 (0%)   11 (9.4%) 2 (18.2%)  
  Hispanic 40 (34.2%) 6 (50.0%)   40 (34.2%) 4 (36.4%)  
  Caucasian 64 (54.7%) 6 (50.0%)   64 (54.7%) 4 (36.4%)  
Median age (minimum-maximum), years 50 (28–73) 53 (42–72) 0.313 50 (28–73) 50 (28–73) 0.084  
  1. aChi-square test. bTFAC (paclitaxel followed by 5-fluoruracil, doxorubicin, and cyclophosphamide) or FAC (5-fluoruracil, doxorubicin, and cyclophosphamide) chemotherapies combined. c P value for comparison of residual cancer burden (RCB)-0 and RCB-I versus RCB-III. PIK3CA, phosphatidylinositol 3-kinase, catalytic, alpha polypeptide.